Spotting charge



March 26, 1968 o. w. BASS 3,374,741

SPOTTING CHARGE Filed Dec. 28, 1965 flLUM/NUM DISC /0 BLACK JPofl'lNG amass, WDER PROPE'LLHNT HND T. POWDERED fllL/MlNU/W /NERT F/LLE R INVENTOR/ 0H1 s (A). Bass a. 0. ATTORNEY United States Patent O 3,374,741 SPOTIING CHARGE Ottis W. Bass, Baltimore, Md., assignor to the United States of America as represented by the Secretary of the Army Filed Dec. 28, 1965, Ser. No. 517,161 3 Claims. (Cl. 10287) ABSTRACT OF THE DISCLOSURE A spotting charge is placed in the nose of a projectile and the spotting charge is ignited by a time delay device at a predetermined time after the projectile is fired.

A spotting charge is placed in the nose of a projectile nance projectile detonations after the projectile is fired from a gun. Time zero, the time of firing of the gun, is readily determined. But, additionally, the time of projectile detonation must be determined with a high degree of precision in order that the precise working time for the fuze may be determined. The problem is difficult where the projectile detonation occurs at a great distance, e.g., 100,000 feet, from the area where the projectile was launched.

In order to determine the moment of detonation, at spotting charge is used to replace the ordinary booster charge and the ordinary main charge is replaced with inert material. The spotting charge must give off large quantities of visible or infrared energy so that sensing equipment at the launching area can detect the exact moment of detonation.

The functioning time of known spotting charges was too great. The functioning times of substantially identical spotting charges would vary too much for high precision timing. Previous spotting charges were not sufficiently hot or bright to reliably trigger infrared or photoelectric timing equipment at great distances.

The present invention helps overcome the noted deficiencies in previous spotting charges.

The single figure is a schematic cross section through one form of the invention.

Projectile 1 contains time fuze 2, black powder pellet 3 and spotting charge 4, which replaces the ordinary booster charge. An inert filler 5 replaces the usual main charge and substantially surrounds spotting charge 4.

Spotting charge 4 comprises special material which is designed to liberate large quantities of infrared energy. An example of the charge material is a 70/30 mix, by weight, of 1,200 grains of propellant, M9 composition, 0.0030 inch web, flaked, for 60 mm. mortar, and 500 grains of aluminum powder, atomized Type C, Class D, loaded into a 3 /2 inch long aluminum liner 11 for deep cavity loaded projectiles. The aluminum liner is capped with a 1% inch diameter aluminum disc 8 with a /2 inch hole 9 in the center. Onion skin paper 10 prevents escape of spotting charge material from liner 11.

The lower end 6 of fuze 2 has a flash passage 7 adjacent to black powder pellet 3.

3,374,741 Patented Mar. 26, 1968 ice M9 composition consists of 57.75% nitro cellulose, 40% nitroglycerin, 1.5% potassium nitrate and 0.75% diphenylamine. Type C atomized aluminum powder consists of granular or spheroidal particles manufactured by the atomizing process. Class D designates 0.95 (minimum) grams per cubic centimeter apparent density.

OPERATION Projectile 1 is fired from a gun and time zero is recorded at the time of firing. Time fuze 2 is activated and a flash produced thereby travels through flash hole 7 to ignite black powder pellet 3. Pellet 3 ignites spotting charge 4 through hole 9 as it ruptures or disintegrates paper 10'.

The example of the spotting charge given hereinabove is important although the exact formula is not deemed absolutely critical. Tests show that a /40 mix and an 80/20 mix give inferior results as compared with the /30 mix. However, a deviation from the 70/30 mix of a few percent may yield substantially equal results.

I claim:

1. Spotting charge material consisting of substantially a 70/30 mix, by weight, of propellant and aluminum powder, said propellant comprising substantially an M9 composition, 0.0030 inch web, flaked.

2. Spotting charge material as in claim 1 wherein said aluminum powder comprises substantially atomized Type C, Class D material.

3. Material as in claim 2 and, an aluminum liner having two ends, closed at one end, substantially surrounding said material, a disc closing the other end of said liner, passage means in said disc, fracturable means closing said passage means, black powder material adjacent to said disc, and a fuze to ignite said black powder.

References Cited UNITED STATES PATENTS 2,900,914 8/1959 Ciccone 10287X 3,013,495 12/1961 Stevenson etal. 10287X 3,291,049 12/1966 Hitchens 102-87 FOREIGN PATENTS 181,169 12/1917 Canada.

607,057 10/1960 Canada.

OTHER REFERENCES Publication of the Ordnance School, Aberdeen Proving Grounds, Md., Aviation Ordnance School Title: Signal Aircraft, Single Star (Final Type); (this reference herein referred to as Single STAR p. 6-243 and 6-243-B, 1942.

Military Explosives; TM 9-1910, April 1955; pp. 274, 284-288 required.

Military Pyrotechnics Series, part three AMC pamphlet N0. AMCP 706-187, October 1963, p. 8 required.

BENJAMIN A. BORCHELT, Primary Examiner.

ROBERT F. STAHL, Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,374,741 March 26, 1968 Ottis W. Bass It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 16, cancel "A spotting charge is placed in the nose of a projectile" and insert A fuze chronograph system is used in analyzing ord- Signed and sealed this 29th day of July 1969.

(SEAL) Attest:

Edward M. Fletcher, Jr.

Attesting Officer Commissioner of Patents WILLIAM E. SCHUYLER; JR. 

